Well control during drilling operations



March 31, 1970 K. 1.. COCHRUM ET 3,

WELL CONTROL DURING DRILLING OPERATIONS Filed April 16, 1968 .4Sheets-Sheet 5 FIG. 5. FIG.6.

3 7 O 1 VI. 6 M 3 3 E 412/ R? N mMM m /7 NCE T 7 EON T 8 l CN A G 2 {1'1W .E l... K H H. F M T TWX AH E NN NH 6 E0 3 KJ March 31, 1970 K.COCHRUM ET AL 3,503,445

WELL CONTROL DURING DRILLING OPERATIONS Filed April 16, 1968 .4Sheets-Sheet 4 FIG. 8.

' INVENTORS. FIG. 9. KENNETH L.COCHRUM,

orm w. KENNEDAY,

BY MW ATTORNEY.

United States Patent "ice US. Cl. 166-244 17 Claims ABSTRACT OF THEDISCLOSURE Method and apparatus for use in controlling wells duringdrilling operations in which drilling fluid is circulated down the drillstring and up the annulus between the drill string and the boreholewall. A tubular member is inserted in the drill string. The tubularmember has arranged thereon a fluid-inflatable packer adapted to closeoff the annulus surrouding the tubular member. Plugs pumped from thesurface cause sleeves arranged within the tubular member to shift underthe application of fluid pressure and open ports and passage to causethe inflatable packer to first close and later reopen the annulus and tobypass the plugged bore of the tubular member. A port may be openedabove the annulus closure upon application of a predetermined fluidpressure to permit fluid to circulate down the drill string and up theannulus between the drill string and the borehole wall. Alternatively,fluid may be applied to the formation surrounding the lower end of thedrill string below the annulus closure by application of a predeterminedfluid pressure in said drill string to unplug the bore of said tubularmember after said inflatable packer has closed off the annulus andbefore the packer has been deflated to open the annulus.

Background of the invention The present invention generally concernsmethod and apparatus for shutting in a well during drilling operations.More particularly, the invention concerns method and apparatus forclosing 011? the annulus between a drill string and a borehole wall andconducting operations thereafter in order to remedy blowouts or otherundesirable well conditions that require correction.

In order to permit remedial action to be taken to control a well in wellin which a blowout has occurred during drilling operations withouthazard, the well is desirably shut in at the bottom of the hole. Ablowout preventer is used to seal the annulus just above the zone thatis providing an influx of fluid (oil, gas or water) caused by thereservoir pressure of that zone being greater than the hydrostaticpressure exerted by the normal circulating drilling fluid. Circulationof fluid above this point allows the well to be controlled withoutfurther influx of reservoir fluids and provides several distinctoperating advantages. The time for well control is reduced. Also,density of the circulating fluid can be increased to the level requiredto control a high pressure zone with minimum time and cost. Mud lossesand mud costs are reduced because it is not necessary to optimize mudweight while attempting to determine or feel for a high pore pressure(e.g., 13 pounds/ gallon equivalent) formation in which to setintermediate casing. Other advantages achieved through the ability tocirculate above the blowout preventer include desired minimization ofsurface casing length and thickness and substantial elimination of thepreviously required intermediate liners; e.g., liners set from 8 to 12thousand feet. Further, faster drilling results from lowered mud weightand improved hydraulics and elimi- 3,503,445 Patented Mar. 31, 1970nation of deliberate drilling rate slow-down to compensate for gascutting of the mud or for potential hazard of crossing poorly definedpressure sealing faults. When the blowout preventer is released, normalcirculation and operations can be restored using a heavier circulatingfluid. The same circulation procedure can be used to allow time forhealing a lost returns zone by keeping a heavy fluid from the lostreturns zone either above or below the blowout preventer. Variations inthe circulation technique will be obvious to those familiar with the artof well control. In addition, the blowout preventer or annulus packofftool may be used to pump heavy fluids and/or cement into high pressureformations to seal and/or abandon the portion of hole below the packofftool. The tool could be left in the hole after such operations and,therefore, be expendible. Other applications for use of the annuluspackofl tool are when a subnormal or a lost circulation zone isencountered in drilling and it becomes desirable to seal off the annulusabove such zone so that lost circulation material or cement can bepumped into the zone at the same time keeping the annulus above the zonefull of fluid for well control purposes.

A primary object of the present invention is to provide improved blowoutprevention apparatus and method for shutting in a well while conductingdrilling operations. Although the invention primarily serves to controlblowouts which occur while drilling the borehole, it is also useful inhealing lost returns zones and aiding in overcoming other problemsencountered during drilling operations.

Summary of the invention In accordance with the teachings of oneembodiment of the invention, the apparatus includes an inflatable packerelement designed to seal in open hole or in casing mounted on a solidtubular member which is insertable in a drill string. The tubular membercontains ports and passageways and two internal slidable sleeves whichpermit inflating and deflating of the packer element. It also contains acirculation port above the packer element which is initially closed by ashear-out plug. The internal sleeves are actuated by pumpdown plugs andsurfaceapplied pump pressure.

In the normal drilling position, the packer element is deflated anddrilling fluid circulation is through the center of the tubular memberwith no obstructions. Both internal shiftable or slidable sleeves aremaintained in place with shear pins. Inflating of the packer element isachieved by pumping down the drill string a plug which engages the lowerinner sleeve. The pins holding the lower inner sleeve shear and thesleeve shifts down to expose a passageway in the tubular memberconnecting the interior of the tubular member and the interior of thepacker element. Check valves located in that passageway retain the fluidwithin the packer element. As the sleeve shifts,

the fluid pressure inflates the packer element and seals the annulus.The check valves trap the pressure and keep the packer element inflated.Circulation above the inflated packer element is achieved by applyingadditional surface pump pressure. At the elevated pressure, theshear-out plugs in the circulation port will release to open the portand permit fluid to flow from within the tubular member into the annulusbetween the tubular member and the well bore wall or casing wall.Deflating of the packer element is accomplished by pumping down thedrill string a second plug slightly larger in diameter than the firstplug to engage the upper inner slidable sleeve. The retaining pin shearsunder surface pump pressure to permit the upper sleeve to move down andexpose packer element deflating and bypass passageways, which permitsthe packer to deflate and fluid circulation to bypass the two plugswithin the tubular member and continue downward through the bit.

In another embodiment of the invention, the apparatus includes aninflatable packer element designed to seal in open hole or in casingmounted on a solid tubular member which is insertable in the drillstring as in the previously described embodiment. The tubular memberalso contains ports and passageways and internal shiftable or slidablesleeves which permit inflating and deflating of the packer element.However, there is no circulation port above the packer element. Theinternal sleeves are actuated by pump-down plugs and surface appliedfluid pressure. After inflating the packer element to close off theannulus, additional fluid pressure applied to the plug in the lowerinternal sleeve causes the plug to shear and reopen the bore of thetubular member to permit fluid to flow through the drill string toformations below the annulus closure.

In the normal drilling position, the packer element is deflated anddrilling fluid circulation is through the center of the tubular memberwith no obstructions. Both internal shiftable or slidable sleeves areheld in place with shearing pins. Inflating of the packer element isachieved by pumping down a plug which engages the lower inner sleeve.The pins holding the lower inner sleeve shear at a predetermined surfacepump pressure and the sleeve shifts down to expose a passageway in thetubular member connecting the interior of the tubular member and theinterior of the packer element. Fluid pressure inflates the packerelement and seals the annulus. The check valves located in thepassageway trap the pressure and keep the packer element inflated.Pumping fluid through the tool is achieved by applying additionalsurface pump pressure which shears out the center portion of thepump-down plug. The sheared out center drops several inches and hangs inthe tubular member. The annulus remains sealed. Deflating of the packerelement is accomplished by shifting the upper inner sleeve downward bypumping down the drill string a second plug, slightly larger in diameterthan the first plug or by use of a sinker bar on a wireline or macaronitubing to shear the sleeve-holding pins. This action exposes deflatingand equalizing ports and allows fluid circulation to bypass the internalplugs and then continue downward through the drill string.Alternatively, the upper plug may be of the shear-through type similarto the lower pump-down plug.

The tubular member is normally positioned just above the drill collarsof the drill string. However, it can be located at other points alongthe drill string. The packer element is capable of sealing the spacebetween the drill string and the well bore either in open hole or incasing. The annulus area below the seal made by the inflated packerelement will be isolated from the annulus area above such seal.

Brief description of the drawings The above object and other objects andadvantages of the invention will be apparent from a more detaileddescription thereof when taken with the drawings wherein:

FIGS. 1-4 are elevational views showing apparatus arranged in accordancewith the invention in four positions of operation: 1) drilling, (2)packer element inflation, (3) circulation above packer element and (4)packer element deflation;

FIGS. 5-7 are elevational views showing apparatus arranged in accordancewith a modification of the invention in three positions of operation:(1) packer element inflating, (2) pumping through and (3) packer elementdeflating;

FIG. 8 is an enlarged view of a shearable plug;

FIG. 9 is a view taken along the line 9-9 of FIG. 8; and

FIG. 10 is a view of the shearable plug in the sheared position.

Detailed description of the invention Referring to the drawings, inFIGS. l4 is shown an annulus packofl tool generally designated 10,adapted to be screw-threadedly connected in a drill string above drillcollars. As shown, tool 10 is a solid tubular member 11 provided with athreaded upper end 12 adapted to be connected to drill pipe and providedwith a flexible, inflatable packer element 15. The lower end of packerelement 15 is secured to a collar 17 initially maintained in place byshear pins 18. An O-ring seal 19 is located on the inner surface ofcollar 17 to provide a seal with the outer surface of tubular member 11.The section of tubular member 11 above packer element 15 is providedwith circulating ports or passageways 20 adapted, when open, to fluidlycommunicate the bore 21 of tubular member 11 and the annulus 22surrounding the tubular member. A packer inflate passageway 23 extendsfrom one of the passageways 20 to the interior of packer element 15. Twocheck valves 24, 25 are arranged in passageway 23. Branching offpassageway 23 above packer element 15 is another passageway 26 formed intubular member 11 which extends to the bore 21 of tubular member 11, butis sealed off from the bore by an upper shiftable or slidable sleeve 27which is initially retained in position in bore 21 by means of shearpins 28. Upper sleeve 27 is provided with a plug seat shoulder 21, ports30 and an outer recessed portion 31. A series of vertically spacedapartO-ring seals are arranged on the inner surface of tubular member 11 forthe purpose of sealing off the various ports and passageways duringoperation of the tool. As shown in FIG. 4, when sleeve 27 is in its downposition, recess 31 fluidly communicates packer deflate passageway 26and a port or passageway 36 which extends between bore 21 of tubularmember 11 and the the annulus surrounding tubular member 11. A lowershiftable or slidable sleeve 40 is initially secured to the bore oftubular member 11 by shear pins 41. Sleeve 40 is provided with a plugseating shoulder 42 and ports 43. Sealing rings 44 are located on theinner surface of tubular member 11 to seal off the inner end ofpassageway 20 when sleeve 40 is in its initial or upper position, asseen in FIG. 1. The outer ends of passageways 20 are initially closed byblowout plugs 46. A plug 50, shown in FIG. 2, is provided with a seatingsurface 51 which engages seat 42 in sleeve 40. It is also preferablyprovided with fishing neck 52 to aid in its removal. A similar butlarger plug 53 is provided with a seating surface 54 which engages seat29 of sleeve 27, as seen in FIG. 4. Plug 53 is also provided with afishing neck 55. A bypass passageway 60 permits fluid circulation aroundplugged bore 21 of tubular member 11.

Operation of embodiment of FIGS. 1-4

The normal drilling position of the tool is shown in FIG. 1. Packerelement 15 is deflated and drilling fluid circulation is down throughthe center of bore 21 of tubular member 11. Both internal shiftingsleeves 27 and 40 are held in place with shear pins 28 and 41,respectively. Packer element 15 is maintained in place by means of shearpin 18.

As illustrated in FIG. 2, packer element 15 is inflated by pumping plugdown the drill string and through a portion of the bore 21 of tubularmember 11 until seating surface 51 of plug 50 engages seating shoulder42 of sleeve 40. Pins 41 shear at a predetermined pressure; e.g., 625p.s.i. surface pump pressure, and sleeve 40 shifts down to its lowerlimit to open the inner end of ports 20 to permit fluid to channelthrough one of the ports 20, check valves 24, 25 and passageway 23 intopacker element 15. As a packer element 15 inflates, shear pin 18 shearsat a predetermined pressure; e.g., 600 p.s.i., and collar 17 slidesupwardly on tubular member 11 allowing packer element 15 to expand andseal off annulus 22.

Circulation above inflated packer element 15 is effected as illustratedin FIG. 3 by applying additional surface pump pressure. At a higherpredetermined pressure, e.g., 1650 p.s.i. surface pump pressure, one ofthe two shearout or blowout plugs 46 releases to open port 20 to permitfluid to move from bore 21 into the annulus above the packer. The othershear-out plug is included for safety purposes.

Deflating of the packer is accomplished, as illustrated in FIG. 4, bypumping down the drill string a second plug 53 which is slightly largerin diameter than plug 50. Seating surface 54 of plug 53 engages seat 29-of sleeve 27 and pin 28 shears at a predetermined pressure, e.g., 625p.s.i. surface pump pressure to permit sleeve 27 to move downwardthereby exposing deflating and bypass passageways to permit fluid toexit from packer element 15 and fluid circulation to bypass the twoplugs through bypass passageway 60 in tubular member 11 and port 43 insleeve 40 and the lower bore 21 of tubular member 11 and pass downwardthrough the drill bit, not shown. The packer fluid passes upwardlythrough packer deflate passageway 26, recess 31 in sleeve 27 and port 36in tubular member 11 into annulus 22 surrounding tubular member 11.

Referring to FIGS. 5-10, there is shown an annulus packolf toolgenerally designated A adapted to be screw-threadedly connected in adrill string above drill collars as in the embodiment of the inventionshown in FIGS. l-4. All of the components of the tool shown in FIGS. 1-4which are identical to the components of the tool shown in FIGS. 5-l0have similar numeral designations. The tool 10A is similar to tool 10,except in tool 10A there is no circulation port or passageway 20. Inaddition, the lower plug member 50A adapated to force lower innershiftable sleeve 40 downwardly is a shearthrough type plug which isshown in detail in FIGS. 8, 9 and 10. Referring to those figures, plug50A is provided with a stationary outer section 56 having an outerseating surface 51A adapted to engage seat 42 of inner sleeve 40. Aslidablev center section 57 of plug 50A is movable downwardly withrespect to section 56 thereof and is initially pinned to section 56 bymeans of shear pin 58. Section 57 is provided with upper shoulders 59which engage the upper end of section 56 when section 57 movesdownwardly relative to section 56. As shown, the upper portion ofsection 57 is formed of crossmembers 62 which provide flow passages whensection 57 is in its lower position. The lower portion of section 57forms a solid piston portion provided with O-ring 61 and closes off thebore of section 56 when in the position shown in FIG. 8. Application ofsurface pump pressure causes shear pin 58 to shear and moves section 17downwardly until shoulders 59 engage the upper end of section 56. Fluidflow is then provided through the plug member 50A by way of the passagesformed by cross-members 62.

Operation of embodiment of FIGS. 5-10 In the normal drilling position ofthe tool, not shown, packer element is deflated and drilling fluidcirculation is down through the center of bore 21 of tubular member 11A.Both internal shifting sleeves 27 and 40 are held in place with shearpins 28 and 41, respectively. Packer element is maintained in place bymeans of shear pin 18.

As illustrated in FIG. 5, packer element 15 is inflated by pumping aplug 50A down the drill string and through a portion of the bore 21 oftubular member 11A to engage seat 42 of sleeve 40. Pins 41 shear at apredetermined pressure, e.g., 625 p.s.i. surface pump pressure, andsleeve 40 shifts to its lower position and opens passageway to permitfluid to channel therethrough past check valves 24 into packer element15. As the packer element inflates, shear pin 18 shears at apredetermined pressure, e.g., 600 p.s.i., and collar 17 slides upwardlyon tubular member 11A.

Pumping fluid through the tool is achieved by applying additionalsurface pump pressure, e.g., 625 p.s.i. which causes shear pin 58 toshear and forces center section 57 of pump-down plug 50A downwardly. Thecenter section drops until shoulders 59 engage the upper end of section56. The annulus remains sealed; however, the flow path through the drillstring is open, as shown in FIG. 6.

Deflating of the packer element 15 is achieved as illustrated in FIG. 7by pumping down the drill string a second plug 53 which is slightlylarger in diameter than plug 50A. Seating surface 54 of plug 53 engagesseat 29 of sleeve 27. Pin 28 shears at a predetermined pressure, e.g.,625 p.s.i. surface pump pressure, and perments sleeve 27 to move downthereby exposing deflating and bypass passageways to permit fluidcirculation to bypass plug 53 through bypass passageway 60 in tubularmember 11A and port 43 in sleeve 40 and pass down through the drill bit,not shown. The packer fluid passes up through packer deflate passageway26, recess 31 in sleeve 27 and port 36 in tubular member 11A and to theannulus surrounding tubular member 11A.

In both embodiments, instead of pump pressure, a sinker bar lowered on awireline or macaroni tubing could be used to shear the sleeve-holdingpins. As shown in FIGS. 5 and 6, a back pressure valve 70 is positionedin the bore of the drill string below packolf tool 10A. This valveallows fluid to be pumped down the drill string but prevents fluid flowupwardly therethrough. Although not shown in FIGS. 14, such a valvecould also be used in the embodiment of the invention described withrespect to those figures. If so used, it would not be necessary tomaintain circulation pressure (drill string pressure above the packofftool) above bottom hole formation pressure.

Changes and modifications may be made in the specific illustrativeembodiments of the invention shown and described herein withoutdeparting from the scope of the invention as defined ino the appendedclaims.

We claim:

1. Apparatus for controlling wells during drilling operationscomprising:

a tubular member insertable in a drill string;

a fluid inflatable packer arranged on said tubular member adapted toclose off the annulus surrounding said tubular member;

a first shiftable sleeve means initially having a flow path therethrougharranged in the bore of said tubular member and adapted to be shiftedfrom a first to a second position when said flow path therethrough hasbeen closed off and fluid pressure applied to such closure;

a second shiftable sleeve means initially having a flow paththerethrough arranged in the bore of said tubular member adapted to beshifted from a first to a second position when said flow paththerethrough has been closed and fluid pressure applied to such closure;

a plurality of fluid passageway means formed in the wall of said tubularmember initially closed by said first and second sleeve means;

said first sleeve means when in said second position thereof opening oneof said fluid passageway means to fluidly communicate said tubularmember bore and the interior of said packer to permit said packer toinflate;

said second sleeve means when in said second position thereof openingother of said fluid passageway means to fluidly communicate the interiorof said packer and the exterior of said tubular member to permit saidpacker to deflate and still other of said fluid passageway means tofluidly communicate the bore of said tubular member above and below saidclosure points to permit fluid flowing downwardly through said drillstring to bypass said closure points.

2. Apparatus as recited in claim 1 including a circulation passagewayformed in the wall of said tubular member adapted to fluidly communicatethe bore of said tubular member and the exterior thereof, said firstsleeve means preventing flow of fluid through said circulationpassageway when in the first position thereof and permitting flow offluid through said circulation passageway when in the second positionthereof, said second sleeve means preventing flow of fluid through saidcirculation passageway when in the second position thereof.

3. Apparatus as recited in claim 1 including said means adapted to closethe flow path through said first sleeve means comprising a first plugmember.

4. Apparatus as recited in claim 3 including means adapted to close theflow path through said second sleeve means comprising a second plugmember having a greater diameter than said first plug member.

5. Apparatus as recited in claim 2 including means arranged in saiddrill string below said tubular member adapted to prevent flow of fluidupwardly therethrough and to permit flow of fluid downwardlytherethrough.

6. Apparatus for controlling wells during drilling operationscomprising:

a tubular member insertable in a drill string;

a fluid inflatable packer arranged on said tubular member adapted toclose off the annulus surrounding said tubular member;

a packer inflate passageway in the wall of said tubular member extendingbetween the bore of said tubular member and the interior of said packer;

valve means arranged in said packer inflate passageway adapted to permitfluid to flow from the bore of said tubular member to the interior ofsaid packer and prevent flow of fluid from the interior of said packerto the bore of said tubular member;

a first packer deflate passageway in the wall of said tubular memberextending between the interior of said packer and the bore of saidtubular member;

a second packer deflate passageway in the wall of said tubular memberextending between the bore of said tubular member and the exterior ofsaid tubular member;

a first sleeve member arranged in the bore of said tubular member andshiftable from a first to a second position and provided with ports andan internal plug seat, said plug seat being adapted to engage a firstplug to close off downward flow of fluid through said tubular memberbore;

a second sleeve member arranged in the bore of said tubular member abovesaid first sleeve member and shiftable from a. first to a secondposition and provided with an external recess, ports and an internalplug seat, said internal plug seat being adapted to engage a second plugto close off downward flow of fluid through said tubular member bore;

a bypass passageway formed in the wall of said tubu lar member adaptedto permit fluid to bypass the bore closures of said sleeve members whensaid first and second plugs engage said respective plug seats;

the first position of said first sleeve member preventing flow of fluidfrom the bore of said tubular member to the interior of said packerthrough said packer inflate passageway;

the first position of said second sleeve member preventing flow of fluidthrough said bypass passageway and through said first and second packerdeflate passageways;

the second position of said first sleeve member permitting fluid flowfrom the bore of said tubular member to the interior of said packerthrough said packer inflate passageway, the ports in said first sleevemem' her being in fluid communication with the other end of said bypasspassageway to permit flow of fluid from said bypass passageway into thebore of said tubular member;

the second position of said second sleeve member permitting flow offluid through said bypass passageway and through said first and secondpacker deflate pas sageways, said first and second packer deflatepassageways fluidly communicating the interior of said packer and theexterior of said tubular member through said recess on said secondsleeve member;

said second sleeve member being moved from said first to said secondposition thereof by application of fluid pressure to said second plug;and

said first sleeve being movable from said first to said second positionthereof by application of fluid pressure to said first plug.

7. Apparatus as recited in claim 6 including:

a fluid circulation passageway formed in the wall of said tubular memberextending between the bore of said tubular member and the exteriorthereof; and

a blowout plug initially closing said circulation passage way, saidblowout plug being adapted to open said circulation passageway uponapplication of fluid pressure thereto, the end of said fluid circulationpassageway opening into the bore of said tubular member being closedwhen said first sleeve member is in said first position thereof andbeing open when said second sleeve member is in said first positionthereof.

8. Apparatus as recited in claim 7 including means ar ranged in saiddrill string below said tubular member adapted to prevent flow of fluidupwardly therethrough and to permit flow of fluid downwardlytherethrough.

9. Apparatus as recited in claim 6 in which said first plug, when seatedin said first sleeve member, is adapted to shear at a predeterminedfluid pressure to permit flow of fluid through said first sleeve member.

10. Apparatus as recited in claim 9 including means arranged in saiddrill string below said tubular member adapted to prevent flow of fluidupwardly therethrough and to permit flow of fluid downwardlytherethrough.

11. A method of controlling formation conditions in a well bore having adrill string with a drill bit on the lower end thereof positionedtherein and which is adapted for circulation of a drilling fluidtherethrough comprising the steps of:

closing off the drill string bore to prevent downward flow of fluidtherethrough only and closing off the annulus between the drill stringand the well hole wall at positions spaced above the drill bit; andpumping and circulating drilling fluid downwardly from the surfacethrough the drill string bore and up the annulus through a bypass pointspaced above the annulus and drill string bore close-off positions andsubsequently opening the bore and annulus and re suming the flow ofdrilling fluid through the drill bit to the bottom of the drill stringand up the an nulus. 12. The method of controlling formation conditionsin a well hole having a drill string with a drill bit on the lower endthereof positioned therein and which is adapted for circulation of adrilling fluid therethrough comprising the steps of:

closing off the bore of said drill string to prevent flow of fluidthrough said drill string bore; closing off the annulus between saiddrill string and the well hole wall; opening the bore of said drillstring to permit fluid to flow dowrr through said drill string and saiddrill bit; closing off the bore of said drill string above the firstdrill string closure point; circulating fluid past said drill stringclosure points and downwardly through said drill bit; and opening theannulus between said drill string and said borehole wall to permit fluidto circulate downwardly through said drill string and said drill bit andup the annulus. 13. The method of controlling formation conditions in awell hole having a drill string with a drill bit on the lower endthereof positioned therein and which is adapted for circulation of adrilling fluid therethrough comprising the steps of closing off thedrill string bore to prevent only downward flow of fluid therethrough ata selected level in said Well; closing off the annulus between the drillstring and well hole Wall adjacent said closure in said drill string;closing off the drill string bore to prevent downward flow of fluidtherethrough at a level above the level of the previous closure of saiddrill string bore; and opening the annulus and circulating fluid downsaid drill string past said closures in said drill string bore throughsaid drill bit and up the annulus.

14. A method as recited in claim 13 in which after the first closure ofsaid drill string bore and closure of said annulus but prior to thesecond closure of said drill string bore, circulating fluid down saiddrill string bore and up the annulus through a bypass point spaced abovethe annulus closure and drill string bore upper closure level.

15. Apparatus for controlling Wells during drilling operationscomprising:

a tubular member insertable in a drill string;

a fluid-inflatable packer arranged on said tubular member adapted toclose off the annulus surrounding said tubular member when inflated;

a plurality of fluid passageway means formed in the wall of said tubularmember including a fluid circulation passageway located above saidpacker adapted to fluidly communicate the bore of said tubular memberand the exterior thereof; movable means arranged in the bore of saidtubular member adapted to open and ciose said fluid passageways to thepassage of fluids therethrough to control inflation and deflation ofsaid packer and circulation of fluid through said circulationpassageway; and means adapted to move said movable means. 16. Apparatusas recited in claim 15 in which said movable means comprises slidablesleeves.

17. Apparatus as recited in claim 16 wherein said means for moving saidslidable sleeves include plug memhers adapted to close the flow pathsthrough said sleeves.

References Cited UNITED STATES PATENTS 2,978,046 4/1961 True 166-1872,994,378 8/1961 Reistle 166-187 3,327,781 6/1967 Nutter 166-1513,427,651 2/1969 Bielstein et a1 166-187 JAMES A. LEPPINK, PrimaryExaminer US. Cl. X.R.

